specific areas occupied by a species that contain features essential to the conservation of the species, and that may require special protection.

Any area of the planet with high biodiversity conservation significance based on the existence of habitat of significant importance to critically endangered or endangered species, restricted range or [..]

regulatory - the areas and habitats identified under the Endangered Species Act that must be protected for a given endangered species to recover or survive

Critical habitat for a threatened or endangered species means:

specific geographic area(s) that contains features essential for the conservation of a threatened or endangered species and that may require special management and protection.

a term used in the Endangered Species Act, includes areas in which are found the physical and biological features essential to the conservation of a species.

Specific areas which possess physical or biological features which are essential to the conservation of a listed species.

Specific geographic areas, whether occupied by a listed species or not, that are essential for its conservation and that have been formally designated by rule published in the Federal Register.

Those areas designated as critical for the survival and recovery of threatened or endangered species (USFS).

As defined in the Species at Risk Act, "critical habitat" means the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species' critical habitat in the recovery strategy or in an action plan for the species.For French see habitat essentiel